Surveying a river launch

Surveying a river launch

Secondary 3
9 marks
Original parallel to supplied E Math applications of trigonometry references

Survey points \(A\) and \(B\) are \(120\text{ m}\) apart on a straight east–west river bank, with \(B\) due east of \(A\).

A launch at \(C\) is on a bearing of \(034^\circ\) from \(A\) and \(307^\circ\) from \(B\).

Give non-exact numerical answers correct to \(3\) significant figures.

  1. Find \(\angle BAC\) and \(\angle ABC\).[2]
  2. Find \(AC\).[3]
  3. Find the area of triangle \(ABC\).[2]
  4. Find the shortest distance from \(C\) to the river bank \(AB\).[2]

Solution:

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Answer:(a) \(56^\circ\), \(37^\circ\) (b) \(72.3\text{ m}\) (c) \(3.60\times10^3\text{ m}^2\) (d) \(60.0\text{ m}\)

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